DP83867CS: DP83867 VI curve for 2.5V IO

greg brandt

Prodigy 20 points

Part Number: DP83867CS
Other Parts Discussed in Thread: DP83869

Tool/software:

I am looking for VI curve data for the DP83867CS PHY for VDDIO at 2.5V.

Table 7.5 of the datasheet illustrates Vol = 0.6V(max) only at 4mA.

My chosen MAC requires 0.5V Vil(max) and has an an Iil of just 50uA.

I am hoping that the VI curve will show alignment between the MAC's requirement and what the PHY can output when relatively lightly loaded.

-Thanks

10 months ago

0 Gerome Cacho 10 months ago

TI__Mastermind 39785 points

Hello,

We do not have a curve, as we expect the supply to be at a constant discrete voltage level. However, we have consumption across temperature, configuration, and at times channel utilization.

https://www.ti.com/lit/an/snla241/snla241.pdf?ts=1729807989334&ref_url=https%253A%252F%252Fwww.google.com%252F

Sincerely,

Gerome

0 greg brandt 10 months ago in reply to Gerome Cacho

Prodigy 20 points

Gerome,
Thanks for the response. The VDDIO voltage level is fixed at 2.5V.
What I am looking for is data on Vol versus Iol on MDIO and RGMII interface pins. See datasheet table 7.5. I am looking for more detail than what is listed there. Specifically, what is Vol when Iol is considerably lower than 4mA.

0 Gerome Cacho 10 months ago in reply to greg brandt

TI__Mastermind 39785 points

Hi Greg,

This data would apply for these pin as they are under the VDDIO domain. Unfortunately, we do not have data for when the driven current is at other conditions than described in the datasheet.

Typically, there isn't much concern regarding driven current when creating a PHY system. So long as VOH/L and VIH/L's line up, this has been sufficient in designing. Is a MAC you are considering sensitive to IIH/L?

Sincerely,

Gerome

0 greg brandt 10 months ago in reply to Gerome Cacho

Prodigy 20 points

That is exactly my issue, Gerome. The VOL and VIL do not line up. On paper, they are off by a measly 100mV. The PHY drives VOL to 0.6V and the MAC requires a VIL of 0.5V. I was kind of surprised that the PHY does not drive lower than 0.6V.

I suspect that when very lightly loaded, the PHY will simply drive (nearly) rail to rail and I will not have a problem at all. Was just looking for some data to back that supposition up.

0 Gerome Cacho 10 months ago in reply to greg brandt

TI__Mastermind 39785 points

Hi Greg,

If the VIL of the MAC is 0.5V at 2.5V VDDIO, perhaps DP83869 may be of better use. I see all VOLs at 0.45V or less.

Sincerely,

Gerome

+1 greg brandt 10 months ago in reply to Gerome Cacho

Prodigy 20 points

Gerome, Thanks, I will look at that.
Is there an IBIS model available for the DP83867?

Cancel that, I found the IBIS model.

Using that model, I was able to simulate the lower IOL ranges. As expected, the PHY does drive pretty much rail to rail. That easily meets my required MAC VIL threshold. I am satisfied with this.

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DP83867CS: DP83867 VI curve for 2.5V IO